The present invention relates to sheet handling apparatus and more particularly to apparatus for loading sheets or plates of glass, or other materials, onto a moving support means for further processing.
While not limited in its use, the apparatus of this invention is of special utility when employed in conjunction with apparatus for the continuous sputter-coating of thin films of metal or a metal alloy upon the surface of glass sheets or other substrates. Sputter-coating involves ion bombarding a target of the coating material in low-pressure gaseous glow discharge to cause particles of the coating material to be dislodged and deposited on the upper surfaces of the substrates to form a continuous film thereon.
One type of coating apparatus for carrying out such a process is disclosed in U.S. Pat. No. 3,904,506, dated Sept. 9, 1975, and embodies a plurality of aligned, independently controlled contiguous chambers including an entry chamber, a coating chamber and an exit chamber, sputter-coating means in the form of a substantially rectangular cathode mounted horizontally in the upper portion of the coating chamber and having a sheet of a selected coating material secured to the bottom thereof, and conveyor means for moving the substrates (glass sheets) in a horizontally disposed position through the successive chambers and beneath the sputter-coating means.
As disclosed in the above patent, the glass sheets or other substrates to be coated are horizontally supported upon and in contact with the upper surfaces of substantially rigid metal platens which convey the glass sheets through the successive chambers of the coating apparatus. While this has proven commercially acceptable, it has been found that, in certain instances, significant improvement can be obtained in the thickness and composition of the coating, as well as the color of the glass sheet at the edges thereof, by overlaying the upper surface of the metal platen with one or more plates of glass and then laying the glass sheets to be coated on the glass overlay and out of contact with the metal platen.
The present invention comprehends the provision of new and improved apparatus for loading the glass sheets to be coated on the support platens in direct contact therewith (or on the glass overlay for the platen, if an overlay is being used). More particularly, the loading apparatus embodies means for automatically depositing glass sheets to be coated horizontally upon successive platens as the said platens and glass sheets are conveyed forwardly in different horizontal planes and preparatory to their being delivered to the coating apparatus.
It has been found that in such a sputter-coating operation, the metal support platens (or the glass overlay therefore) must be completely free of dust, dirt and other foreign matter when the glass sheets are placed thereon and also that the glass sheets themselves must be maintained free of all contaminates during the loading of them onto the platens and until they are introduced into the coating apparatus.
To accomplish these objectives, the loading apparatus of this invention contemplates the provision of means for effectively removing any dust, dirt and other foreign matter from both the support platen (or overlay therefore) before the glass sheets are deposited thereon and from the glass sheets during the loading of them onto the platen and their transfer into the coating apparatus.
Other objects and advantages of the invention will become apparent from the following description when taken in connection with the accompanying drawings.